1. Technical Field
The present invention relates to a radiographic imaging device.
2. Related Art
In recent years, FPDs (flat panel detectors), in which a radiation-sensitive layer is disposed on a TFT (thin film transistor) active matrix substrate and radiation can be directly converted to digital data, have been made practical. Using these FPDs and the like, portable radiographic image imaging devices (below referred to as electronic cassettes) have been made practical, in which image information that represents a radiographic image expressed by irradiated radiation is generated and the generated image information is stored.
In such an electronic cassette, when a voltage of a predetermined voltage level for driving the FPD is to be obtained from a battery, it is generally more efficient in terms of energy to convert a voltage level of supplied electricity by switching control with a switching power supply, such as a DC-DC converter or the like, to obtain the voltage of the predetermined voltage level.
Japanese Patent Application Laid-Open (JP-A) No. 2005-6888 discloses details of boosting a voltage level of electricity provided from a battery and obtaining electricity to be used in driving of an FPD.
However, with a switching power supply, voltage-boosting is implemented by performing switching control of switching elements. Therefore, although the energy efficiency is good, power supply noise such as voltage ripples and the like arises because of switching frequencies in the power supply circuitry, and is manifested as image noise in radiographic images.
Accordingly, as a technology that suppresses line noise arising in captured images because of random noise components that are generated in power supply circuitry such as a series regulator or the like, JP-A No. 2003-163343 has described details of connecting a low pass filter (LPF) to the power supply circuitry and supplying a reference potential that passes through the low pass filter.
When, using the technology of JP-A No. 2003-163343, a low pass filter is provided on an electricity line used in driving of an FPD, a noise reduction effect to a certain extent is expected. However, for the supply of electric power, it is necessary to continuously operate the power supply circuitry during image-reading operations via switching elements of a switching regulator type, such as a DC-DC converter or the like, or of a charge pump type or the like. In practice therefore, microscopic ripples passing through the LPF are manifested in images, and this technology is insufficient as a countermeasure against noise.